1 /*
2 * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /*
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file:
31 *
32 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
33 *
34 * All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions are met:
38 *
39 * * Redistributions of source code must retain the above copyright notice,
40 * this list of conditions and the following disclaimer.
41 *
42 * * Redistributions in binary form must reproduce the above copyright notice,
43 * this list of conditions and the following disclaimer in the documentation
44 * and/or other materials provided with the distribution.
45 *
46 * * Neither the name of JSR-310 nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
61 */
62 package java.time;
63
64 import java.io.IOException;
65 import java.io.ObjectInputStream;
66 import static java.time.LocalTime.NANOS_PER_MINUTE;
67 import static java.time.LocalTime.NANOS_PER_SECOND;
68
69 import java.io.Serializable;
70 import java.util.Objects;
71 import java.util.TimeZone;
72 import sun.misc.VM;
73
74 /**
75 * A clock providing access to the current instant, date and time using a time-zone.
76 * <p>
77 * Instances of this class are used to find the current instant, which can be
78 * interpreted using the stored time-zone to find the current date and time.
79 * As such, a clock can be used instead of {@link System#currentTimeMillis()}
80 * and {@link TimeZone#getDefault()}.
81 * <p>
82 * Use of a {@code Clock} is optional. All key date-time classes also have a
83 * {@code now()} factory method that uses the system clock in the default time zone.
84 * The primary purpose of this abstraction is to allow alternate clocks to be
85 * plugged in as and when required. Applications use an object to obtain the
86 * current time rather than a static method. This can simplify testing.
87 * <p>
88 * Best practice for applications is to pass a {@code Clock} into any method
89 * that requires the current instant. A dependency injection framework is one
90 * way to achieve this:
91 * <pre>
92 * public class MyBean {
93 * private Clock clock; // dependency inject
94 * ...
95 * public void process(LocalDate eventDate) {
96 * if (eventDate.isBefore(LocalDate.now(clock)) {
97 * ...
98 * }
99 * }
100 * }
101 * </pre>
102 * This approach allows an alternate clock, such as {@link #fixed(Instant, ZoneId) fixed}
103 * or {@link #offset(Clock, Duration) offset} to be used during testing.
104 * <p>
105 * The {@code system} factory methods provide clocks based on the best available
106 * system clock This may use {@link System#currentTimeMillis()}, or a higher
107 * resolution clock if one is available.
108 *
109 * @implSpec
110 * This abstract class must be implemented with care to ensure other classes operate correctly.
111 * All implementations that can be instantiated must be final, immutable and thread-safe.
112 * <p>
113 * The principal methods are defined to allow the throwing of an exception.
114 * In normal use, no exceptions will be thrown, however one possible implementation would be to
115 * obtain the time from a central time server across the network. Obviously, in this case the
116 * lookup could fail, and so the method is permitted to throw an exception.
117 * <p>
118 * The returned instants from {@code Clock} work on a time-scale that ignores leap seconds,
119 * as described in {@link Instant}. If the implementation wraps a source that provides leap
120 * second information, then a mechanism should be used to "smooth" the leap second.
121 * The Java Time-Scale mandates the use of UTC-SLS, however clock implementations may choose
122 * how accurate they are with the time-scale so long as they document how they work.
123 * Implementations are therefore not required to actually perform the UTC-SLS slew or to
124 * otherwise be aware of leap seconds.
125 * <p>
126 * Implementations should implement {@code Serializable} wherever possible and must
127 * document whether or not they do support serialization.
128 *
129 * @implNote
130 * The clock implementation provided here is based on {@link System#currentTimeMillis()}.
131 * That method provides little to no guarantee about the accuracy of the clock.
132 * Applications requiring a more accurate clock must implement this abstract class
133 * themselves using a different external clock, such as an NTP server.
134 *
135 * @since 1.8
136 */
137 public abstract class Clock {
138
139 /**
140 * Obtains a clock that returns the current instant using the best available
141 * system clock, converting to date and time using the UTC time-zone.
142 * <p>
143 * This clock, rather than {@link #systemDefaultZone()}, should be used when
144 * you need the current instant without the date or time.
145 * <p>
146 * This clock is based on the best available system clock.
147 * This may use {@link System#currentTimeMillis()}, or a higher resolution
148 * clock if one is available.
149 * <p>
150 * Conversion from instant to date or time uses the {@linkplain ZoneOffset#UTC UTC time-zone}.
151 * <p>
152 * The returned implementation is immutable, thread-safe and {@code Serializable}.
153 * It is equivalent to {@code system(ZoneOffset.UTC)}.
154 *
155 * @return a clock that uses the best available system clock in the UTC zone, not null
156 */
157 public static Clock systemUTC() {
158 return new SystemClock(ZoneOffset.UTC);
159 }
160
161 /**
162 * Obtains a clock that returns the current instant using the best available
163 * system clock, converting to date and time using the default time-zone.
164 * <p>
165 * This clock is based on the best available system clock.
166 * This may use {@link System#currentTimeMillis()}, or a higher resolution
167 * clock if one is available.
168 * <p>
169 * Using this method hard codes a dependency to the default time-zone into your application.
170 * It is recommended to avoid this and use a specific time-zone whenever possible.
171 * The {@link #systemUTC() UTC clock} should be used when you need the current instant
172 * without the date or time.
173 * <p>
174 * The returned implementation is immutable, thread-safe and {@code Serializable}.
175 * It is equivalent to {@code system(ZoneId.systemDefault())}.
176 *
177 * @return a clock that uses the best available system clock in the default zone, not null
178 * @see ZoneId#systemDefault()
179 */
180 public static Clock systemDefaultZone() {
181 return new SystemClock(ZoneId.systemDefault());
182 }
183
184 /**
185 * Obtains a clock that returns the current instant using best available
186 * system clock.
187 * <p>
188 * This clock is based on the best available system clock.
189 * This may use {@link System#currentTimeMillis()}, or a higher resolution
190 * clock if one is available.
191 * <p>
192 * Conversion from instant to date or time uses the specified time-zone.
193 * <p>
194 * The returned implementation is immutable, thread-safe and {@code Serializable}.
195 *
196 * @param zone the time-zone to use to convert the instant to date-time, not null
197 * @return a clock that uses the best available system clock in the specified zone, not null
198 */
199 public static Clock system(ZoneId zone) {
200 Objects.requireNonNull(zone, "zone");
201 return new SystemClock(zone);
202 }
203
204 //-------------------------------------------------------------------------
205 /**
206 * Obtains a clock that returns the current instant ticking in whole seconds
207 * using best available system clock.
208 * <p>
209 * This clock will always have the nano-of-second field set to zero.
210 * This ensures that the visible time ticks in whole seconds.
211 * The underlying clock is the best available system clock, equivalent to
212 * using {@link #system(ZoneId)}.
213 * <p>
214 * Implementations may use a caching strategy for performance reasons.
215 * As such, it is possible that the start of the second observed via this
216 * clock will be later than that observed directly via the underlying clock.
217 * <p>
218 * The returned implementation is immutable, thread-safe and {@code Serializable}.
219 * It is equivalent to {@code tick(system(zone), Duration.ofSeconds(1))}.
220 *
221 * @param zone the time-zone to use to convert the instant to date-time, not null
222 * @return a clock that ticks in whole seconds using the specified zone, not null
223 */
224 public static Clock tickSeconds(ZoneId zone) {
225 return new TickClock(system(zone), NANOS_PER_SECOND);
226 }
227
228 /**
229 * Obtains a clock that returns the current instant ticking in whole minutes
230 * using best available system clock.
231 * <p>
232 * This clock will always have the nano-of-second and second-of-minute fields set to zero.
233 * This ensures that the visible time ticks in whole minutes.
234 * The underlying clock is the best available system clock, equivalent to
235 * using {@link #system(ZoneId)}.
236 * <p>
237 * Implementations may use a caching strategy for performance reasons.
238 * As such, it is possible that the start of the minute observed via this
239 * clock will be later than that observed directly via the underlying clock.
240 * <p>
241 * The returned implementation is immutable, thread-safe and {@code Serializable}.
242 * It is equivalent to {@code tick(system(zone), Duration.ofMinutes(1))}.
243 *
244 * @param zone the time-zone to use to convert the instant to date-time, not null
245 * @return a clock that ticks in whole minutes using the specified zone, not null
246 */
247 public static Clock tickMinutes(ZoneId zone) {
248 return new TickClock(system(zone), NANOS_PER_MINUTE);
249 }
250
251 /**
252 * Obtains a clock that returns instants from the specified clock truncated
253 * to the nearest occurrence of the specified duration.
254 * <p>
255 * This clock will only tick as per the specified duration. Thus, if the duration
256 * is half a second, the clock will return instants truncated to the half second.
257 * <p>
258 * The tick duration must be positive. If it has a part smaller than a whole
259 * millisecond, then the whole duration must divide into one second without
260 * leaving a remainder. All normal tick durations will match these criteria,
261 * including any multiple of hours, minutes, seconds and milliseconds, and
262 * sensible nanosecond durations, such as 20ns, 250,000ns and 500,000ns.
263 * <p>
264 * A duration of zero or one nanosecond would have no truncation effect.
265 * Passing one of these will return the underlying clock.
266 * <p>
267 * Implementations may use a caching strategy for performance reasons.
268 * As such, it is possible that the start of the requested duration observed
269 * via this clock will be later than that observed directly via the underlying clock.
270 * <p>
271 * The returned implementation is immutable, thread-safe and {@code Serializable}
272 * providing that the base clock is.
273 *
274 * @param baseClock the base clock to base the ticking clock on, not null
275 * @param tickDuration the duration of each visible tick, not negative, not null
276 * @return a clock that ticks in whole units of the duration, not null
277 * @throws IllegalArgumentException if the duration is negative, or has a
278 * part smaller than a whole millisecond such that the whole duration is not
279 * divisible into one second
280 * @throws ArithmeticException if the duration is too large to be represented as nanos
281 */
282 public static Clock tick(Clock baseClock, Duration tickDuration) {
283 Objects.requireNonNull(baseClock, "baseClock");
284 Objects.requireNonNull(tickDuration, "tickDuration");
285 if (tickDuration.isNegative()) {
286 throw new IllegalArgumentException("Tick duration must not be negative");
287 }
288 long tickNanos = tickDuration.toNanos();
289 if (tickNanos % 1000_000 == 0) {
290 // ok, no fraction of millisecond
291 } else if (1000_000_000 % tickNanos == 0) {
292 // ok, divides into one second without remainder
293 } else {
294 throw new IllegalArgumentException("Invalid tick duration");
295 }
296 if (tickNanos <= 1) {
297 return baseClock;
298 }
299 return new TickClock(baseClock, tickNanos);
300 }
301
302 //-----------------------------------------------------------------------
303 /**
304 * Obtains a clock that always returns the same instant.
305 * <p>
306 * This clock simply returns the specified instant.
307 * As such, it is not a clock in the conventional sense.
308 * The main use case for this is in testing, where the fixed clock ensures
309 * tests are not dependent on the current clock.
310 * <p>
311 * The returned implementation is immutable, thread-safe and {@code Serializable}.
312 *
313 * @param fixedInstant the instant to use as the clock, not null
314 * @param zone the time-zone to use to convert the instant to date-time, not null
315 * @return a clock that always returns the same instant, not null
316 */
317 public static Clock fixed(Instant fixedInstant, ZoneId zone) {
318 Objects.requireNonNull(fixedInstant, "fixedInstant");
319 Objects.requireNonNull(zone, "zone");
320 return new FixedClock(fixedInstant, zone);
321 }
322
323 //-------------------------------------------------------------------------
324 /**
325 * Obtains a clock that returns instants from the specified clock with the
326 * specified duration added
327 * <p>
328 * This clock wraps another clock, returning instants that are later by the
329 * specified duration. If the duration is negative, the instants will be
330 * earlier than the current date and time.
331 * The main use case for this is to simulate running in the future or in the past.
332 * <p>
333 * A duration of zero would have no offsetting effect.
334 * Passing zero will return the underlying clock.
335 * <p>
336 * The returned implementation is immutable, thread-safe and {@code Serializable}
337 * providing that the base clock is.
338 *
339 * @param baseClock the base clock to add the duration to, not null
340 * @param offsetDuration the duration to add, not null
341 * @return a clock based on the base clock with the duration added, not null
342 */
343 public static Clock offset(Clock baseClock, Duration offsetDuration) {
344 Objects.requireNonNull(baseClock, "baseClock");
345 Objects.requireNonNull(offsetDuration, "offsetDuration");
346 if (offsetDuration.equals(Duration.ZERO)) {
347 return baseClock;
348 }
349 return new OffsetClock(baseClock, offsetDuration);
350 }
351
352 //-----------------------------------------------------------------------
353 /**
354 * Constructor accessible by subclasses.
355 */
356 protected Clock() {
357 }
358
359 //-----------------------------------------------------------------------
360 /**
361 * Gets the time-zone being used to create dates and times.
362 * <p>
363 * A clock will typically obtain the current instant and then convert that
364 * to a date or time using a time-zone. This method returns the time-zone used.
365 *
366 * @return the time-zone being used to interpret instants, not null
367 */
368 public abstract ZoneId getZone();
369
370 /**
371 * Returns a copy of this clock with a different time-zone.
372 * <p>
373 * A clock will typically obtain the current instant and then convert that
374 * to a date or time using a time-zone. This method returns a clock with
375 * similar properties but using a different time-zone.
376 *
377 * @param zone the time-zone to change to, not null
378 * @return a clock based on this clock with the specified time-zone, not null
379 */
380 public abstract Clock withZone(ZoneId zone);
381
382 //-------------------------------------------------------------------------
383 /**
384 * Gets the current millisecond instant of the clock.
385 * <p>
386 * This returns the millisecond-based instant, measured from 1970-01-01T00:00Z (UTC).
387 * This is equivalent to the definition of {@link System#currentTimeMillis()}.
388 * <p>
389 * Most applications should avoid this method and use {@link Instant} to represent
390 * an instant on the time-line rather than a raw millisecond value.
391 * This method is provided to allow the use of the clock in high performance use cases
392 * where the creation of an object would be unacceptable.
393 * <p>
394 * The default implementation currently calls {@link #instant}.
395 *
396 * @return the current millisecond instant from this clock, measured from
397 * the Java epoch of 1970-01-01T00:00Z (UTC), not null
398 * @throws DateTimeException if the instant cannot be obtained, not thrown by most implementations
399 */
400 public long millis() {
401 return instant().toEpochMilli();
402 }
403
404 //-----------------------------------------------------------------------
405 /**
406 * Gets the current instant of the clock.
407 * <p>
408 * This returns an instant representing the current instant as defined by the clock.
409 *
410 * @return the current instant from this clock, not null
411 * @throws DateTimeException if the instant cannot be obtained, not thrown by most implementations
412 */
413 public abstract Instant instant();
414
415 //-----------------------------------------------------------------------
416 /**
417 * Checks if this clock is equal to another clock.
418 * <p>
419 * Clocks should override this method to compare equals based on
420 * their state and to meet the contract of {@link Object#equals}.
421 * If not overridden, the behavior is defined by {@link Object#equals}
422 *
423 * @param obj the object to check, null returns false
424 * @return true if this is equal to the other clock
425 */
426 @Override
427 public boolean equals(Object obj) {
428 return super.equals(obj);
429 }
430
431 /**
432 * A hash code for this clock.
433 * <p>
434 * Clocks should override this method based on
435 * their state and to meet the contract of {@link Object#hashCode}.
436 * If not overridden, the behavior is defined by {@link Object#hashCode}
437 *
438 * @return a suitable hash code
439 */
440 @Override
441 public int hashCode() {
442 return super.hashCode();
443 }
444
445 //-----------------------------------------------------------------------
446 /**
447 * Implementation of a clock that always returns the latest time from
448 * {@link System#currentTimeMillis()}.
449 */
450 static final class SystemClock extends Clock implements Serializable {
451 private static final long serialVersionUID = 6740630888130243051L;
452 private static final long OFFSET_SEED =
453 System.currentTimeMillis()/1000 - 1024; // initial offest
454 private final ZoneId zone;
455 // We don't actually need a volatile here.
456 // We don't care if offset is set or read concurrently by multiple
457 // threads - we just need a value which is 'recent enough' - in other
458 // words something that has been updated at least once in the last
459 // 2^32 secs (~136 years). And even if we by chance see an invalid
460 // offset, the worst that can happen is that we will get a -1 value
461 // from getNanoTimeAdjustment, forcing us to update the offset
462 // once again.
463 private transient long offset;
464
465 SystemClock(ZoneId zone) {
466 this.zone = zone;
467 this.offset = OFFSET_SEED;
468 }
469 @Override
470 public ZoneId getZone() {
471 return zone;
472 }
473 @Override
474 public Clock withZone(ZoneId zone) {
475 if (zone.equals(this.zone)) { // intentional NPE
476 return this;
477 }
478 return new SystemClock(zone);
479 }
480 @Override
481 public long millis() {
482 // System.currentTimeMillis() and VM.getNanoTimeAdjustment(offset)
483 // use the same time source - System.currentTimeMillis() simply
484 // limits the resolution to milliseconds.
485 // So we take the faster path and call System.currentTimeMillis()
486 // directly - in order to avoid the performance penalty of
487 // VM.getNanoTimeAdjustment(offset) which is less efficient.
488 return System.currentTimeMillis();
489 }
490 @Override
491 public Instant instant() {
492 // Take a local copy of offset. offset can be updated concurrently
493 // by other threads (even if we haven't made it volatile) so we will
494 // work with a local copy.
495 long localOffset = offset;
496 long adjustment = VM.getNanoTimeAdjustment(localOffset);
497
498 if (adjustment == -1) {
499 // -1 is a sentinel value returned by VM.getNanoTimeAdjustment
500 // when the offset it is given is too far off the current UTC
501 // time. In principle, this should not happen unless the
502 // JVM has run for more than ~136 years (not likely) or
503 // someone is fiddling with the system time, or the offset is
504 // by chance at 1ns in the future (very unlikely).
505 // We can easily recover from all these conditions by bringing
506 // back the offset in range and retry.
507
508 // bring back the offset in range. We use -1024 to make
509 // it more unlikely to hit the 1ns in the future condition.
510 localOffset = System.currentTimeMillis()/1000 - 1024;
511
512 // retry
513 adjustment = VM.getNanoTimeAdjustment(localOffset);
514
515 if (adjustment == -1) {
516 // Should not happen: we just recomputed a new offset.
517 // It should have fixed the issue.
518 throw new InternalError("Offset " + localOffset + " is not in range");
519 } else {
520 // OK - recovery succeeded. Update the offset for the
521 // next call...
522 offset = localOffset;
523 }
524 }
525 return Instant.ofEpochSecond(localOffset, adjustment);
526 }
527 @Override
528 public boolean equals(Object obj) {
529 if (obj instanceof SystemClock) {
530 return zone.equals(((SystemClock) obj).zone);
531 }
532 return false;
533 }
534 @Override
535 public int hashCode() {
536 return zone.hashCode() + 1;
537 }
538 @Override
539 public String toString() {
540 return "SystemClock[" + zone + "]";
541 }
542 private void readObject(ObjectInputStream is)
543 throws IOException, ClassNotFoundException {
544 // ensure that offset is initialized
545 is.defaultReadObject();
546 offset = OFFSET_SEED;
547 }
548 }
549
550 //-----------------------------------------------------------------------
551 /**
552 * Implementation of a clock that always returns the same instant.
553 * This is typically used for testing.
554 */
555 static final class FixedClock extends Clock implements Serializable {
556 private static final long serialVersionUID = 7430389292664866958L;
557 private final Instant instant;
558 private final ZoneId zone;
559
560 FixedClock(Instant fixedInstant, ZoneId zone) {
561 this.instant = fixedInstant;
562 this.zone = zone;
563 }
564 @Override
565 public ZoneId getZone() {
566 return zone;
567 }
568 @Override
569 public Clock withZone(ZoneId zone) {
570 if (zone.equals(this.zone)) { // intentional NPE
571 return this;
572 }
573 return new FixedClock(instant, zone);
574 }
575 @Override
576 public long millis() {
577 return instant.toEpochMilli();
578 }
579 @Override
580 public Instant instant() {
581 return instant;
582 }
583 @Override
584 public boolean equals(Object obj) {
585 if (obj instanceof FixedClock) {
586 FixedClock other = (FixedClock) obj;
587 return instant.equals(other.instant) && zone.equals(other.zone);
588 }
589 return false;
590 }
591 @Override
592 public int hashCode() {
593 return instant.hashCode() ^ zone.hashCode();
594 }
595 @Override
596 public String toString() {
597 return "FixedClock[" + instant + "," + zone + "]";
598 }
599 }
600
601 //-----------------------------------------------------------------------
602 /**
603 * Implementation of a clock that adds an offset to an underlying clock.
604 */
605 static final class OffsetClock extends Clock implements Serializable {
606 private static final long serialVersionUID = 2007484719125426256L;
607 private final Clock baseClock;
608 private final Duration offset;
609
610 OffsetClock(Clock baseClock, Duration offset) {
611 this.baseClock = baseClock;
612 this.offset = offset;
613 }
614 @Override
615 public ZoneId getZone() {
616 return baseClock.getZone();
617 }
618 @Override
619 public Clock withZone(ZoneId zone) {
620 if (zone.equals(baseClock.getZone())) { // intentional NPE
621 return this;
622 }
623 return new OffsetClock(baseClock.withZone(zone), offset);
624 }
625 @Override
626 public long millis() {
627 return Math.addExact(baseClock.millis(), offset.toMillis());
628 }
629 @Override
630 public Instant instant() {
631 return baseClock.instant().plus(offset);
632 }
633 @Override
634 public boolean equals(Object obj) {
635 if (obj instanceof OffsetClock) {
636 OffsetClock other = (OffsetClock) obj;
637 return baseClock.equals(other.baseClock) && offset.equals(other.offset);
638 }
639 return false;
640 }
641 @Override
642 public int hashCode() {
643 return baseClock.hashCode() ^ offset.hashCode();
644 }
645 @Override
646 public String toString() {
647 return "OffsetClock[" + baseClock + "," + offset + "]";
648 }
649 }
650
651 //-----------------------------------------------------------------------
652 /**
653 * Implementation of a clock that adds an offset to an underlying clock.
654 */
655 static final class TickClock extends Clock implements Serializable {
656 private static final long serialVersionUID = 6504659149906368850L;
657 private final Clock baseClock;
658 private final long tickNanos;
659
660 TickClock(Clock baseClock, long tickNanos) {
661 this.baseClock = baseClock;
662 this.tickNanos = tickNanos;
663 }
664 @Override
665 public ZoneId getZone() {
666 return baseClock.getZone();
667 }
668 @Override
669 public Clock withZone(ZoneId zone) {
670 if (zone.equals(baseClock.getZone())) { // intentional NPE
671 return this;
672 }
673 return new TickClock(baseClock.withZone(zone), tickNanos);
674 }
675 @Override
676 public long millis() {
677 long millis = baseClock.millis();
678 return millis - Math.floorMod(millis, tickNanos / 1000_000L);
679 }
680 @Override
681 public Instant instant() {
682 if ((tickNanos % 1000_000) == 0) {
683 long millis = baseClock.millis();
684 return Instant.ofEpochMilli(millis - Math.floorMod(millis, tickNanos / 1000_000L));
685 }
686 Instant instant = baseClock.instant();
687 long nanos = instant.getNano();
688 long adjust = Math.floorMod(nanos, tickNanos);
689 return instant.minusNanos(adjust);
690 }
691 @Override
692 public boolean equals(Object obj) {
693 if (obj instanceof TickClock) {
694 TickClock other = (TickClock) obj;
695 return baseClock.equals(other.baseClock) && tickNanos == other.tickNanos;
696 }
697 return false;
698 }
699 @Override
700 public int hashCode() {
701 return baseClock.hashCode() ^ ((int) (tickNanos ^ (tickNanos >>> 32)));
702 }
703 @Override
704 public String toString() {
705 return "TickClock[" + baseClock + "," + Duration.ofNanos(tickNanos) + "]";
706 }
707 }
708
709 }